The present invention relates generally to a compact size tape cassette which is smaller in size to a standard size tape cassette used widely in magnetic recording and/or reproducing apparatus such as home video tape recorders (VTRs), and hence requires an adapter when used in the home video tape recorders. More particularly, this invention relates to a compact size tape cassette having an improved pair of brake mechanisms associated with a supply reel hub and a take-up reel hub, respectively, in interlocked relation to one another to perform a reel hub releasing operation simultaneously and reliably.
As is well known, a standard size tape cassette is used widely in home video tape recorders. There has been developed a compact size tape cassette which is smaller in size than the standard size tape cassette and can be recorded and reproduced by the home video tape recorder while the compatibility with the standard size tape cassette is maintained.
The compact size tape cassette can be recorded and reproduced not only by a compact video tape recorder of a construction for exclusive use with the compact size tape cassette, but also by the home video tape recorders of a construction for exclusive use with the standard size tape cassette. In the latter case, however, the compact size tape cassette must be accommodated in a tape cassette adapter having a size identical to the size of the standard size tape cassette.
Aside from the spread of the home video tape recorders, an all-in-one video camera and recorder called a VTR with camera has recently been manufactured. In the VTR with camera, the compact size tape cassette of a smaller size than the standard size tape cassette is used in order to reduce the size and weight of the VTR with camera, thereby improving the portability of the VTR with camera.
FIG. 31 of the accompanying drawings is a perspective view of a compact size tape cassette 1 shown with its guard panel or lid disposed in the open position.
The compact size tape cassette 1, as shown in FIG. 31, includes a magnetic tape 2 contained in a housing 3 composed of an upper shell 4 and a lower shell 5 assembled together, and a guard panel or lid 6 hinged to opposite side walls of the housing 3 for opening and closing a front opening of the housing 3. Designated by 16 is a vertical pin-receiving hole for receiving a brake-releasing pin, 21 a take-up reel hub, and 25 a supply reel hub.
The magnetic tape 2 extends across the front opening of the housing 3 while they are guided around left and right guide rollers 10, 10 provided at opposite ends of the front opening. The magnetic tape 2 is protected by the lid 6 which is normally disposed in the closed position. The lower shell 5 has a cutout recess 11 through which a toothed gear 23 formed on a periphery of a lower annular flange 22 of the take-up reel hub 21 faces to the right side wall (left-hand side in FIG. 31) of the housing 3. The recess 11 is defined when the upper and lower shells 4 and 5 are assembled. The lid 6 is selectively held in the open position and the closed position in a clicking manner by means of a slider 14 which is urged forwardly into snapping engagement with a portion of the lid 6 by the force of a plate spring 13 fitted in a U-shaped groove 12 in the right side wall of the housing 3. The housing 3 also has a vertical positioning groove 15 for preventing mis-loading of the compact size tape cassette 1. The positioning groove 15 is formed behind the recess 11 and extends substantially across the height of the upper and lower shells 4 and 5.
When the compact size tape cassette 1 of the foregoing construction is used in a compact video tape recorder (not shown), it is loaded from an opening into the body of the compact video tape recorder until its arrival at a predetermined position in which the lid 6 is pivoted to the substantially horizontal open position such as shown in FIG. 31. Then, the compact size tape cassette 1 is lowered so that a supply reel hub 25 fits with a supply reel disc (not shown) and the toothed gear 23 on the periphery of the lower annular flange 22 of the tape-up reel hub 21 meshes with a drive gear (not shown) of the compact video tape recorder. In this instance, two pairs of vertical and oblique loading pins (not shown) and a capstan (not shown) are received in first, second and third recesses 7, 8 and 9, respectively, at the front side of the compact size tape cassette 1.
The compact size tape cassette 1 thus loaded can be recorded and/or reproduced by the compact video tape recorder.
On the other hand, when the compact size tape cassette 1 is used in a home video tape recorder (not shown), it is loaded by using either a tape cassette adapter which, as shown in Japanese Utility Model Publication No. 60-37739, has a size identical to the size of the standard size tape cassette, or a cassette tray on which a standard size tape cassette and a compact size tape cassette are placed.
As described above, the standard size tape cassette and the compact size tape cassette used in the video tape recorders include a housing containing a pair of reel hubs around which a magnetic tape is wound. In the recording and reproducing modes of operation, the magnetic tape wound on the supply reel hub is pulled out from the front opening of the housing, then travels along a magnetic head of the video tape recorder, subsequently returns from the front opening into the housing, and finally is wound on the take-up reel hub. In the rewinding mode of operation, the magnetic tape is fed directly from the take-up reel hub to the supply reel hub.
Each of the supply reel hub and the take-up reel hub is provided with a brake mechanism which is operative to prevent the corresponding reel hub from rotating accidentally. When the housing is subjected to an impact force or shock during transportation or handling of the tape cassette, the supply reel hub or the take-up reel hub tends to turn accidentally, thereby placing the magnetic tape into a slackened condition which will cause various deficiencies such as uneven rotation of the reel hubs, folding of the magnetic tape, and rupturing of the magnetic tape. These deficiencies can be overcome by the brake mechanisms associated with the reel hubs.
FIG. 32 is a perspective view of the compact size tape cassette, with the upper shell omitted for clarity.
As shown in FIG. 32, the supply reel hub 25 and the take-up reel hub 21 are received in the lower shell 5 with the magnetic tape wound around the reel hubs 21, 25. The supply reel hub 25 and the take-up reel hub 21 are provided with the corresponding ones of the brake mechanisms. A take-up reel stopper 31 is non-rotatably mounted on a support shaft 17 upstanding from a portion of an inside surface of the lower shell 5 adjacent to the take-up reel hub 21.
The brake mechanism associated with the supply reel hub 25 includes, as shown in FIG. 33, a plurality of circumferentially spaced radial ribs 18 disposed on an under surface of a lower annular flange 26 of the supply reel hub 25, and a plurality of circumferentially spaced radial ribs 19 disposed on an inside surface of the lower shell 5 in confronting relation to the radial ribs 18. The ribs 18 and the ribs 19 have a trapezoidal cross-section. In the assembled condition shown in FIG. 31, the supply reel hub 25 is urged downwardly toward the inside surface of the lower shell 5 by means of a reel spring (not shown) fixedly mounted on the inside surface of the upper shell 4. In this instance, the ribs 18 on the under surface of the lower annular flange 26 of the supply reel hub 25 mesh with ribs 19 on the lower shell 5 to provide a braking effect on the supply reel hub 25 so that the supply reel hub 25 is normally locked in position against rotation relative to the lower shell 5.
Thus, the brake mechanism associated with the supply reel hub 25 is composed of the radial ribs 18 on the under surface of the lower annular flange 26 of the supply reel hub 25 and the radial ribs 19 on the inside surface of the lower shell 5.
This brake mechanism is released when, after the compact size tape cassette is loaded in a video tape recorder, a supply reel spindle of the video tape recorder or of the tape cassette adapter is inserted into the supply reel hub 25 from the bottom thereof and lifts up the supply reel hub 25 from the inside surface of the lower shell 5, thereby disengaging the radial ribs 18 and the radial ribs 19.
The brake mechanism associated with the take-up reel hub 21 includes, as shown in FIG. 34, a plurality of downwardly facing triangular teeth 32 disposed on a lower part of the take-up reel stopper 31 non-rotatably mounted on the support shaft 17 upstanding from a portion of the inside surface of the lower shell 5 adjacent to the take-up reel hub 21. The reel stopper 31 is urged downwards by means of a spring (not shown) so that the teeth 32 of the reel stopper 31 are brought into meshing engagement with the toothed gear 23 on the periphery of the lower flange 22 of the take-up reel hub 21 to provide a braking effect on the take-up reel hub 21. Thus, the take-up reel hub 21 is normally locked in position against rotation relative to the lower shell 5.
As appears clear from the foregoing description, the brake mechanism associated with the take-up reel hub 21 is composed of the non-illustrated spring, the triangular teeth 32 of the reel stopper 31, and the toothed gear 23 on the periphery of the lower flange 22 of the take-up reel hub 21.
This brake mechanism is released when, after the compact size tape cassette is loaded in a video tape recorder, a brake-releasing pin (not shown) of the video tape recorder is inserted into the pin-receiving hole 16 in the lower shell 5 from the bottom thereof and lifts up the take-up reel stopper 31 from the inside surface of the lower shell 5, thereby disengaging the teeth 32 on the take-up reel stopper 31 and the teethed gear 23 on the take-up reel hub 21.
However, since the braking operation of the brake mechanisms, which are associated with the supply and take-up reel hubs 25, 21 of the conventional compact size tape cassette 1 shown in FIGS. 31 through 34, relies on the force of the springs, the reel hubs 25, 21 are likely to turn against the force of the springs when an external shock is imparted on the compact size tape cassette 1.
In addition, the conventional brake mechanisms are unable to retain the magnetic tape 2 within the housing 3 when the magnetic tape 2 is pulled out while the lid 6 is being manually opened.
With the foregoing drawbacks of the conventional compact side tape cassette in view, various improvements have been proposed by the present assignee, as described in U.S. patent application Ser. No. 07/744,436 filed Aug, 13, 1991. According to a preferred embodiment described in the prior application, there is provided a compact size tape cassette which comprises a supply reel hub and a take-up reel hub rotatably mounted within a housing, with a magnetic tape wound around the reel hubs, and a pair of brake mechanisms associated with the take-up reel hub and supply reel hub, respectively, for locking the reel hubs in position against rotation relative to the housing, wherein the brake mechanisms are interlocked such that a releasing operation of one brake mechanism is transmitted to the other brake mechanism for causing a releasing operation of the other brake mechanism in synchronism with the releasing operation of the one brake mechanism.
In the compact size tape cassette of the prior application, the supply reel hub and the take-up reel hub are rotatable in one direction to wind up the magnetic tape but they are prevented by the brake mechanisms from rotating in the opposite direction to slacken the magnetic tape. With this construction, when the magnetic tape is slacken due to some reasons, or when the user misunderstands a normal play of the magnetic tape as a slack, an attempt by the user to take up the slack may result in over-tensioning of the magnetic tape. If such over-tensioning occurs, a displaceable reel hub, namely the supply reel hub is pulled by the tension of the magnetic tape toward a path of movement of the magnetic tape, thus making it difficult to receive the compact size tape cassette in a tape cassette adaptor or to load the compact size tape cassette in a compact video tape recorder.
This difficulty has been overcome by a compact size tape cassette according to another preferred embodiment of the invention described in the prior application, in which the brake mechanisms are automatically released by a brake-releasing mechanism when the compact size tape cassette is received in the tape cassette adaptor or loaded in the compact video tape recorder even if the magnetic tape is over-tensioned.
The last-mentioned compact size tape cassette is not fully satisfactory in that when the tape cassette with its magnetic tape held in an over-tensioned condition is allowed to stand without being received in the cassette tape adaptor or loaded in the compact video tape recorder, the over-tensioned magnetic tape is likely to be permanently stretched or otherwise deformed or to deform a structural part of the tape cassette which is provided to guide the magnetic tape.